The present invention relates to an optical apparatus such as a digital still camera, a video camera, and an interchangeable lens, and to an optical apparatus having an optical image stabilizer that shifts an image stabilizing element such as a lens to perform optical image stabilization (image shake correction).
Many optical apparatuses include an optical image stabilizer that shifts a lens with respect to an optical axis of an optical system in order to reduce image shake caused by shake such as hand jiggling.
Such an optical image stabilizer has a shake sensor which detects the shake of the optical apparatus in a pitch direction and a yaw direction, and an actuator which shifts the lens with respect to the optical axis based on outputs from the shake sensor. Moreover, many optical image stabilizers include a lock mechanism which limits (locks) the shift of the lens so that the lens is unexpectedly shifted with respect to the optical axis of the optical system when an image stabilizing operation is not performed.
Japanese Patent No. 3618798 discloses an example as a lock mechanism. In this lock mechanism, a rotatable lock member is always biased toward a lock position by spring force. When an image stabilizing operation is performed, the lock member is rotated to a lock-releasing position by an actuator (motor), and is attracted by an electromagnet to be held at the lock-releasing position.
Further, Japanese Patent Laid-Open No. 10-142647 discloses a lock mechanism in which a rotatable lock member is driven by a stepping motor.
However, in the lock mechanism disclosed in Japanese Patent No. 3618798, it is necessary to hold the lock member at the lock-releasing position by energizing the electromagnet during the image stabilizing operation. Therefore, it is necessary to continue energization of the electromagnet during the image stabilizing operation, which increases power consumption.
On the other hand, in the lock mechanism disclosed in Japanese Patent Laid-Open No. 10-142647, the lock member can be held at the lock-releasing position by utilizing cogging force (self-holding force) generated in the stepping motor in a non-energized state, which results in a reduction in power consumption. However, when rotating force which exceeds the cogging force and is caused by external force such as impact acts on the lock member, the lock member is rotated from the lock-releasing position, which may bring discontinuance of the image stabilizing operation.